So why didn't anyone think of this before.  This simple tool is a jeweler's dream for soldering rings when resizing.  Just fill the cup with cold water and submerge the stone and mounting while soldering the shank.  The stone is kept cool in the water.   Simple, effective.  Soldering cup includes special sized negative locking tweezers designed to sip on and off the post.  This is a tool for virtually every jeweler.